About fifteen years ago when Ford Motor Company began using its patented push-on couplings marketed as Ford Spring-Lock.RTM. fittings in assembling its vehicle air conditioning systems, it created an acute vehicle service industry problem due to the high incidence of failure of the O-rings used to seal the connection between the push-on fitting and the caged pipe to which the push-on fitting is coupled.
Two solutions to the foregoing problem were patented by George Corzine, namely, U.S. Pat. No. 4,728,130 and U.S. Pat. No. Re. 33,946. Hundreds of thousands of axially split clamps made according to U.S. Pat. No. Re. 33,946 have been sold and used successfully on Ford Spring-Lock couplings to prevent the failure of the coupling's two O-rings.
However, the outside diameter of the push-on fittings of Ford's Spring-Lock couplings is not rigidly controlled and this fact has in some instances caused undesirable deformation of oversized Ford push-on fittings when the fitting is clamped by an axially split clamp made according to U.S. Pat. No. Re. 33,946.
Ford's Spring-Lock couplings are made in six sizes to couple together the various sizes of tubing used in the air conditioning systems of its Ford, Mercury, Lincoln and other vehicles. Each Spring-Lock coupling includes a caged pipe whose cage includes a garter-type coiled spring, a cylindrical push-on fitting whose end is flared to fit and lock within the cage of the pipe, and a pair of O-rings designed to seal the connection between the pipe and the push-on fitting.
Axially split clamps made according to U.S. Pat. No. Re. 33,946 are made both of metal and of molded plastic and all of them include semi-circular or arcuate surfaces which, when the clamp is screwed together, apply a strong, inwardly directed substantially 360.degree. pressure to the outer surface of the push-on fitting which locks the pipe and push-on fitting in strict axial alignment and prevents rupture of the O-ring seal between the fitting and the pipe. However, if the outer diameter of the push-on fitting is oversized, when the axially split clamp is screwed together, the inwardly directed pressure of the clamp may be sufficient to deform the normally cylindrical form of the thin walled push-on fitting.